Unidentified Longhorned Borer Larva

larvae ID Attached is a picture of a larvae caught near our cabin in Arnold Ca (Calaveras County). Can you help me identify what pest this is? We have lost one pine tree to it and may lose others given the drought conditions. Thanks. Larry Rillera

Hi Larry, This is some species of Long Horned Borer Beetle in the family Cerambycidae. Probably nothing short of disection and DNA analysis will get you an exact species. If your goal is an exact species, you will need to research which members of the family feed on pine in your locality and try to narrow the possibilities from there. BugGuide is a great source for information. Beetle larvae in general are much more difficult to identify than caterpillars. We will see if Eric Eaton can provide a novice’s guide to differentiating Cerambycids from Buprestids, the two main wood boring families of beetles.

Update: (06/14/2008) Daniel: Ok, how to tell whether it is a longhorn beetle grub (Cerambycidae) or a metallic woodborer larva (family Buprestidae). Well, in the larval stage, cerambycids are known as “roundheaded borers” while buprestids are called “flatheaded borers.” Indeed, it would appear as though the front quarter of a buprestid larva has been flattened like a pancake, greatly expanded on either side, followed behind by a much more slender body. Roundheaded borers are not flattened, though may show some depressed areas on the thorax, as the specimen in this image shows. Buprestid larvae, as they bore, leave behind them fine, tightly-packed “frass,” often in a ringed or fingerprint pattern. “Frass” is a polite name for insect poop, and it amounts to sawdust for woodborers. Roundheaded borers leave behind very coarse, fibrous frass. Apparently, a foolproof way to differentiate the two is thus: buprestid larvae have a hardened plate on the first segment behind the head, both on top and underneath. Cerambycid larvae lack the plate on the underside (per Western Forest Insects by R.L. Furniss and V.M. Carolin, 1977, U.S. Department of Agriculture Miscellaneous Publication No. 1339). Hope that clarifies things (seems like one has to put everything under a scope to tell the difference….). Take it easy. Great work as always on everything else. Eric